If your room is truly small, or you want space for a chair as well, a loveseat or a settee is often the better answer. It seats two, which is how most of us actually use a sofa on a weeknight, and it leaves room for an armchair that can be turned toward conversation.

A settee is a little different from a loveseat. It usually sits higher, with a more upright back and exposed legs, which makes it feel lighter and more like furniture than a big soft pile. McGee & Co.'s Clemence at 60 inches, and their Gemma and Magda at 65, are all elegant, the kind of thing that looks right in an older apartment with tall windows. Lulu and Georgia's Sawni settee is similar in spirit with a softer line.

Loveseats are lower and cushier, for lying down with a film. George Oliver's Decato is tufted and mid-century, and House of Hampton's Carolina is a classic upholstered shape. Lulu and Georgia's Nelja by Sarah Sherman Samuel and Anthropologie's Denver are modular, which I love for small spaces, because you can add a seat later if you move somewhere bigger.

Legs matter more than you would think. A sofa raised on visible legs shows floor underneath, and seeing floor makes a room feel bigger. A skirted sofa, or one that sits flat on the ground, looks heavier even at the same size. If you are torn between two, choose the one on legs.

The most underrated small-space sofa is the one without arms. Removing the arms can save a surprising amount of length, which means you can fit a proper sofa where a loveseat with chunky arms would barely squeeze in. It also makes the piece feel open and easy to perch on from any side.

Lulu and Georgia's Sloman is a modular armless sofa that reads very clean and modern. Anthropologie's Celine comes in corduroy, soft and a little retro, and their Bowen is another modular armless option that you can arrange in a line or split into two seats. For the smallest rooms, Etta Avenue's Leona is a 47-inch armless velvet two-seater, barely bigger than an armchair.

The trade-off with armless pieces is that there is nothing to lean on. I solve that with two firm pillows at each end and a side table close enough to rest an elbow and a mug. It also helps to push an armless sofa against a wall or back it with a console, so it feels anchored rather than floating in the middle of the room.

What I would skip: a sectional in a small living room, unless it is truly the only seating. It fills the corner, blocks the walkway and leaves no room for a second chair. A compact sofa and one armchair will almost always seat more people, more comfortably, and they are far easier to get up the stairs.

Every small living room I have loved had a sofa that was slightly smaller than I thought I wanted. It left room to walk, room for a chair and room for the rug to show, and that is what made the space feel calm.

If you take one thing away, let it be this: measure depth and arm width, not just length, and tape the footprint on your floor before you order. Leave at least a couple of feet to walk in front of it. Once you see the outline on the floor, you will know within a minute whether it works, and you will never have to explain why the closet door only opens halfway. Then add one comfortable chair, and the room will seat more people than a bigger sofa ever could.